Photo: Earth Selfie.

 
Hour One
Liz Peek, Fiscal Times. Dan Henninger, WSJ Editorial. Francis Rose, WJLA. Brian Benstock, Paragon Honda.
Hour Two
Michael Vlahos, Johns Hopkins. Gregory Copley, Defense & Foreign Affairs.
 
Hour Three
Hotel Mars: David Livingston; Geoffrey Landis, NASA. Robert Nelson, PERC.
Hour Four
Steve Warner @DarkCityFM. Henry Miller, Hoover. Shami Chatterjee, Cornell.